Syria's government and opposition sat around a negotiating table for the first time today, but they appeared no closer to finding a common position on the nation's future.
Delegates used their opening speeches in the Swiss town of Montreux to list atrocities allegedly committed by the other side in the conflict.
UN Secretary General Ban Ki-Moon insisted the focus of the talks must be to establish a transitional government in Syria, but the thorny issue of President Assad's role within that seemed as intractable as ever.
The conflict in Syria has been raging for almost three years, resulting in more than 130,000 deaths and millions of homeless refugees.
ITV News' Middle East Correspondent Geraint Vincent reports from Montreux:
UN Secretary General Ban Ki-Moon opened the conference with the words: "Hope exists but it's fragile".
The mood of optimism was quickly shattered as Syria's foreign minister Walid al-Moualem delivered his opening remarks, accusing foreign powers of "supporting terrorism".
He insisted Assad's future was not in question, saying: "Nobody in this world has a right to withdraw legitimacy from a president or government ... other than the Syrians themselves."
Syria's ambassador to the UN clashed with ITV News' correspondent Geraint Vincent for suggesting that Assad could not realistically keep his position:
The opposition representative Ahmed Jarba called on the Syrian government delegation to immediately sign the Geneva agreement, transferring power away from Assad.
US Secretary of State John Kerry - who has sponsored the talks with his Russian counterpart Sergei Lavrov - said he saw only one option moving forward: "That Bashar al-Assad will not be part of that transition government."
Despite the disagreements, the special envoy to Syria Lakhdar Brahimi sounded a note of optimism, suggesting that both Syrian delegations appeared willing to discuss prisoner swaps and ceasefires.
Russia's foreign minister Sergei Lavrov urged both sides not to focus exclusively on leadership change, telling reporters: "For the first time in three years of the bloody conflict ... the sides - for all their accusations - agreed to sit down at the negotiating table."